Engine downsizing comes with downside

[wemay]

Originally Posted By: Virtus_Probi
One way to help avoid LSPI in a DIT engine is to use oil that doesn't promote it.
dexos1 Gen 2 includes an LSPI test in a GM DIT engine and I will sure be looking for that license when it goes live in September. Interestingly enough, it looks like M1 5W30 AP already has a Gen 2 license number.
Here is a good thread that wemay started discussing LSPI and oil, there are more in the "Interesting Articles" forum.

Oronite on LSPI

dexos1 Gen 2 Licenses

BTW, I am interested in LSPI because my car was recalled for it...


SPOT ON!

 

[demarpaint]

Originally Posted By: Quattro Pete
Originally Posted By: Lolvoguy
"there's no replacement for displacement"

And small displacement may require frequent replacement.

 

[CT8]

Originally Posted By: Linctex
Originally Posted By: meep

turbocharging is not new---


Just think - the 1987 Buick GNX (underrated at 276 hp from 231 cubes) was 30 YEARS ago!!!
Turbocharged middle 1060's Corvair !

 

[CT8]

Originally Posted By: Alfred_B
Electric cars will fix this issue.
Where will the electricity come from to charge the batteries?

 

[Lolvoguy]

Originally Posted By: Quattro Pete
Originally Posted By: Lolvoguy
"there's no replacement for displacement"

And small displacement may require frequent replacement.

 

[Kuato]

Nothing new really..."don't lug your engine" is something our granddads said way back when.

 

[CR94]

Originally Posted By: Kuato
Nothing new really..."don't lug your engine" is something our granddads said way back when.
What's new is that modern LSPI destroys the engine, whereas way back when "lugging," if not extreme, didn't, and was more efficient than the opposite error of needless high revs.

 

[SubLGT]

http://articles.sae.org/15481/

Quote:
Researchers want to address LSPI triggers as a way to reduce or eliminate these unwanted, uncontrolled events. “If oil droplets are pushed into the combustion chamber, an LSPI event is likely. It’s also likely to occur in the hot spots,” Dr. Wagenblast said, referencing specific combustion chamber areas, such as where the fuel injector’s spray bloom hits the piston bowl and the high-temperature surfaces of exhaust valves.

Certain driving scenarios can be LSPI event triggers. “It depends very much on how the vehicle is driven,” he said. “For example, if you’re driving a pickup truck or an SUV with a heavy tow-load and you stomp on the accelerator, an LSPI event will probably happen.”

LSPI test cycle component failures include damage to the coatings, skirts and ring lands of pistons. Mahle engineers are evaluating several potential solutions for increasing component robustness, such as incorporating a high-strength ring carrier into a piston’s first ring land.


Makes me wonder about LSPI in the 2.7L twin turbo motor in the F150 when it is towing

 

[PimTac]

I'm guessing it's the newer materials in engines that cannot hold up under knocking. Those of us who drove in the 70-80's will remember engines that knocked constantly. It was actually said that light pinging meant good fuel economy. Back then they didn't have lightweight pistons, low friction rings, and other components that are in modern engines today. Knock sensors are standard as well.

 

[JimPghPA]

.

 

[cb_13]

Originally Posted By: Lolvoguy
"there's no replacement for displacement"

I'm pretty sure every modern engine has proven that to be false.

Technology is the replacement.

 

[OneEyeJack]

If engineering and cost accounting is the art of doing just enough and no more then they'll just have to tell the engine computer not to allow LSPI. In other words, blame it on the software.

 

[SilverFusion2010]

Originally Posted By: SubLGT
http://articles.sae.org/15481/

Quote:
Researchers want to address LSPI triggers as a way to reduce or eliminate these unwanted, uncontrolled events. “If oil droplets are pushed into the combustion chamber, an LSPI event is likely. It’s also likely to occur in the hot spots,” Dr. Wagenblast said, referencing specific combustion chamber areas, such as where the fuel injector’s spray bloom hits the piston bowl and the high-temperature surfaces of exhaust valves.

Certain driving scenarios can be LSPI event triggers. “It depends very much on how the vehicle is driven,” he said. “For example, if you’re driving a pickup truck or an SUV with a heavy tow-load and you stomp on the accelerator, an LSPI event will probably happen.”

LSPI test cycle component failures include damage to the coatings, skirts and ring lands of pistons. Mahle engineers are evaluating several potential solutions for increasing component robustness, such as incorporating a high-strength ring carrier into a piston’s first ring land.


Makes me wonder about LSPI in the 2.7L twin turbo motor in the F150 when it is towing


They have the electronic throttle and transmission programmed to avoid it. There is no throttle cable remember. When you floor it under load all the software has to do is tell the transmission to unlock the torque converter and downshift before the throttle plate pops open. Voila you've avoided an lspi event by unloading the engine and allowing it to rev and catch a gear instead of lugging THEN shifting.

 

[gregk24]

Originally Posted By: Kibitoshin
Not really a huge fan where a turbo on a tiny engine makes most of it's power. I doubt morons who drive these things will keep it out of boost to reap the fuel economy benefits.


Morons? Wow thanks! I'm a fan of VW turbos, they seem to be tuned very well.

 

[RooflessVW]

Originally Posted By: Kibitoshin
Not really a huge fan where a turbo on a tiny engine makes most of it's power. I doubt morons who drive these things will keep it out of boost to reap the fuel economy benefits.

You don't like peak torque just off idle? :screwy:

 

[gregk24]

Originally Posted By: rooflessVW
Originally Posted By: Kibitoshin
Not really a huge fan where a turbo on a tiny engine makes most of it's power. I doubt morons who drive these things will keep it out of boost to reap the fuel economy benefits.

You don't like peak torque just off idle? :screwy:


For real! Having said that there is something satisfying about revving out a N/A Honda, best of both worlds below...

 

[edyvw]

Originally Posted By: Kibitoshin
Not really a huge fan where a turbo on a tiny engine makes most of it's power. I doubt morons who drive these things will keep it out of boost to reap the fuel economy benefits.

Pease do tell us how you keep it "out of boost?"

 

[Tomioka]

Heh I guess you guys got me. Apologies for the moron comment. To tell you the truth I've never driven a turbocharged vehicle and I'm impressed with the power it puts out like the Ford Ecoboost 3.5L. Still not a huge fan of these high strung small displacement engines in terms of reliability though.

But for me it's N/A V8's till I die.

 

[Shannow]

Slightly off topic, but my 2.8 Colorado is boosting moving out of the carpark cold.

LSPI is different to what we all used to know in the old engine days.

The cylinder USED to be full of a homogenous(ish) charge of air and fuel. The fuel at the "ends" of the combustion chamber got forced into squish and quench areas, and top ring grooves, and either got absorbed into the layr of oil on the wall, or just squeezed into a crevice where it couldn't burn.

On the expansion and exhaust stroke, these unburned hydrocarbons were desorbed, or released from the crevices and contributed to HC (and CO to an extent) in the exhaust.

DI, these locations are full of air...and oil mist.

Where these places used to be filled with something that had SOME octane rating, we didn't see ring lands getting blown off from underneath (yes, you could cave them in with regular pinging/knocking), now it's like a little diesel engine that CAN operate in the top ring groove.

Very different to times past.

But, I've been driving D.I. diesels for 14 years, and don't recall the issues ever emerging on them, so not sure what/why it become an SI engine problem.

 

[SonofJoe]

For what it's worth, I don't honestly believe the LSPI situation can be described as 'dire'.

Is LSPI real? Yes.

Is it unpredictable? Yes, very.

Is it well understood? It wasn't originally but for the most part, yes it is now.

Given that there are already hundreds of thousands of potentially LSPI-susceptable TGDI engined vehicles already out there on the roads, how many have seen severe engine damage? Hmmm...either no-one knows or the people that might know aren't saying. I think the people that are most affected (people who make pistons like Mahle and the OEMs) are deliberately hyping LSPI up to get attention focussed on the issue. My own (admittedly cynical) guess is the total number of engines affected worldwide is in the tens, probably not the hundreds and certainly not the thousands. You should also bear in mind that not all damaged piston lands are down to LSPI. If you over-boost any stock engine (like the VW Twin Turbo) where the pistons lack the mechanical integrity to withstand the forces imposed, you're asking for trouble.

Is there a solution? Yes, don't lug the engine or drive up steep hills, towing a boat in top gear. Funnily enough, most sensible people don't do this as a matter of course. Also you can use a synthetic oil with a Magnesium based detergent system. This widely proven and simple solution could have been implemented in a heartbeat but oh nooooooo! That's far too simple!

According to The Powers That Be, before we do anything for drivers of TGDI engined cars, we have to ensure that ALL oils everywhere never ever cause LSPI. So first we must develop an industry standard LSPI test and we must put this at the heart of GF-6. Of course this takes forever to implement (they're saying 2019 at the earliest now but on past performance, I'd expect this to slip significantly). And all the time TGDI engined run, for the most part, quite happily on bog-standard Calcium detergent based oils, the more apparent it becomes that LSPI is something that neurotic OEMs and parts makers WORRY ABOUT but actually isn't that big a deal for the car buying public.